Honestly, it is like the term 'blog' has replaced what would have been known as a 'webpage' in the early 90's; the single page, personal site. Since people have gotten more technically savvy with their HTML, everything has become topic-oriented webSITEs, and the personal page has kind of died. To me, the blog thing is a return to that idea.
That said, I don't think it will ever "die", but anything so broadly defined is gonna suffer a bit of drift. You don't know what you are gonna get when you visit a blog. I remember the first blogs I ever went to were long lists of interesting "FYI" links with short descriptions. Now they can be akin to a diary, a soapbox, a tutorial, pretty much anything.
I think 'blogging' will just subdivide and acquire more complex taxonomy as their content grows more varied and people want to frequent particular flavors.